Travelstart/CarTrawler doesn't want to issue a Tax Invoice after taking my deposit

I booked a car with Travelstart and the money was deducted from my business account by Travelstart. The car was subcontracted to First Car Rental. I received 2 invoices from First Car for the fuel and tyre damage but they could give me a Tax Invoice for the deposit paid. When contacting them they said that Travelstart (CarTrawler) is the broker and they must give me a Tax Invoice. After spending 2 (super frustrating) days on email, Whatsapp and telephone calls CarTrawler still haven't issued me with an invoice, they just sent me a receipt. They say First Car must issue it and First Car say CarTrawler must issue it. What a joke! I have NEVER received such bad service from a car hire agency/broker and will NEVER make use of their car hire service ever again!! Useless and unhelpfull service at its worst!!!